I would just go. Worst case is they ask you to leave.
After looking at your sig it looks like you're equipped to shoot in low light...that's good. I took most of my stuff at ISO 1600, f/2.8 (thank god for this Tamron lens), and around 40/50 shutter. I still had too brighten a lot of them up in post. I guess that's the sacrifice. Some beautiful lighting in there, though.